High speed spindle construction



2 sheets-Sheet 1 A. H. DALL ET AL HIGH SPEED SPINDLE CONSTRUCTION FiledJune 23, 1937 fam/mai //m l1 ATTORNEY.

Aug. 29, 1939.

A. H. DALL ET A| 2,171,208

HIGH SPEED SPINDLE CONSTRUCTION Filed June 23, 1937 2 Sheets-Sheet 2Aug. 29, 1939.

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I ATTORNEY;

flange portion I6 on one end, is insertedl in.

Patented Aug. 29, 1939 UNITED STATES PATENT OFFICE ,man SPEED sPmDLEcoNs'rmJcTIoN Albert n. m11, silerton, and Frederick s. Haas,Cincinnati, Ohio, assignors to Cincinnati Grinders Incorporated,Cincinnati, Ohio, a

corporation of Ohio Application June 23, 1937, Serial No. 149,854

5 Claims.

This invention relates to machine tools and more particularly to animproved form of high speed spindle construction for the rotary toolsthereof.

One of the objects of this invention is to provide means for supportinga machine tool spindle for high speed rotation.

Another object of this invention is to provide improved means lforanti-frictionally supporting a spindle for high spe'ed rotation and atthe same time maintaining the plane of rotation of the cutting tool,such as a grinding wheel, in a predetermined plane Within precisionlimits.

Other objects and advantages of the present invention should be readilyapparent by reference.to the following specification considered in.

conjunction with the accompanying drawings illustrative of oneembodiment thereof, but it will be understood that any modifications maybe made in the specific structural details within the scope oftheappended claims without departing from or exceeding the spirit of theinvention.v

Referring to the drawings in which like reference numerals indicate likeor similar parts:

'Figure 1 is a sectional view of a high speed spindle constructionembodying the principles of this invention.

Figure 2 is a Section on the line 2-2 of Figure 1.

Figure 3 is a section on the ure 1. v IFigure 4 is a sectional viewshowing a, modied form of the invention.

line 3-3 of Fig- Figure 5 is a detail view of one lof the 'double Itapered rocker shoes shown in Figure 4.

Figure 6 is an end view of the s hoe shown in Figure 5.

Figure 7 is a schematic diagram showing the relationship vof the anglesof the double tapered shoe with respect to the axis of the spindle.

Figure 8 is an enlarged detail of one of the shoes shown in-Figure 4.Figure 9 is a detail view showing the details of the .thrust bearingshown in Figure 1.

In Figure 1 of the drawings, the reference numeral IIJ indicates a partof the structure of a. machine too'l, such as a grinding machine, saidstructure comprising spaced walls II and I2 having aligned openings I3and I4 respectively formed therein. A sleeve I5, having a these openingswith the flange I6 abutting one side ofthe wal1 .I2, and held in placeby a nut l1 threaded on vthe end of the sleeve and engaging the outside0f the wall II. The sleeve rests on the bottom of the openings I3 and I4and is held against rotation by a plurality of dowel pins I8 and I9, andis prevented from lifting by means of set screws 20 and 2|.

The sleeve I5 has aligned bores 22 and 23 formed in opposite endsthereof and a tool spindle 24, which is disposed in the sleeve, hasreduced journals 25 and 26 passingthrough these aligned bores.

One end of the spindle 24 has a shoulder 21, against which an annularguard 28 is adapted to be positioned. A grinding wheel 29 is positionedon the spindle with one side in engagement with the central boss 30 ofthe guard 28 and held against rotation by a clamping screw 3| whichengages an enlarged flange 32 mounted on the other side of the grindingwheel, said screw being threaded in an axial bore in the end of thespindle.

The grinding wheel may be provided with a trued surface 33 of precisionwidth which is adapted to fit into and engage a recess 34 in a workpiece 35 for finishing the bottom surface of said recess. Since thegrinding wheel'is small, it must be rotated at a high rate for obtainingthe desired surface speed.

In order to obtain the necessary speed of rotation with a minimum amountof power, a form of anti-friction bearing means is provided forsupporting the spindle at spaced points which will permit of high speedsof rotation. A plurality of rocker shoe bearing members 36 are providedin the bore 23 of the sleeve I5 for engagement with the journal 26 ofthe spindle. Each of these rocker shoe members is provided With a boss31 on the outside periphery, as shown in Figure 8, the radius of thecurvature of which is less than the radius of the bore 23 whereby onlyline contact Ais made between the shoe and the bore, so that the shoe isfree to pivot a lim- 'ited amount. A set screw 38 is provided forholding the shoe in position circumferentially and at the same timepermitting the pivoted movement. The bearing surface 39 of the. shoe hasa beveled endlso that rotation of the shaft in its prescribed'directionlwill cause oil to be' drawnv in between the shoe and the journal andcause a hydrostatic pressure to be generated by the hydrodynamicalcondition in the oil film. The variations in the pressure of the fluidwill cause the shoe, to rock avery limited amount about its pivot byline contact with the spindle The thickness of the shoe and Oil lmcetermines the position of the axis of the shaft with 55 .off asuiiicient amount to permit free rotation of the spindle.

A similar set of bearing shoes is provided in the bore 22 and by thesame method of set up, it will be apparent that it is possible to alignthe axis of the spindle parallel to the axis of bores 22 and 23.

To obtain the best results these bearings I should be supplied withlubricating oil under some pressure, and to this end the sleeve i5 isprovided with openings 4I through which oil may be introducedfto theinterior of the sleeve from a suitably located reservoir or from a pump.In order that a pressure may be built up within the sleeve, oil sealsare provided at each end of the sleeve and to accommodate these, eachendl of the sleeve is counterbored as at d2 and d3 to form shouldersagainst which the sealing members dll and Ll5 may bear. These membershave a running t with the shaft and are held against the shoulders bysprings 56, which are held in position by cup shaped members -dll,threaded into the counterbores. Since there is very little leakage pastthese seals, it will be apparent that a substantial pressure may bebuilt up within the sleevev to' maintain the desired supply of lubricantto all of the bearing shoes so that the necessary hydrostatic pressurewill be generated `for supporting the spindle.

The spindle 24 is provided with a tapered portion 68 upon which is keyeda driving pulley 49. A belt 50 may be passed around this pulley foractuating the same.

It will be noted that since the rocker shoe bearing surface extendsparallel to the surface of the spindle, it is free to move axially,which would make the position of the grinding wheel 33 with respect tothe Work uncertain, and therefore means have been provided forstabilizing the axial position of the spindle. One form that this meansmay take is shown in Figures 1 and 9, and comprises a thrust bearing 5Iconsisting of an inner race member 52 which is xed with the spindle andan outer race member 53 which isv held in a. fixed`position in thehousing 515. A lubricant reservoir 55 may be attached to the housing 54and' connected by a channel 56 for lubrication of the thrust bearing.

If so desired, the thrust bearing shown in Fig- The spindle 2d isprovided with double tapered journals 6| and 62 and it will be notedfrom Figure '7 that a line of contact between the tapered journal andthe spindle, and lying in a radial plane, such as the line 63wi1l makean acute angle 6d with the axis of the spindle. The shoes 51 areprovided with hardened inserts 65 having conical recesses 55 forreceiving the end of locking screws-Gl.

There are three shoes 51 equally spaced about the periphery of thedouble cone journals on the spindle andthe method of set up is the sameas that previously described in connection with the plane rocker shoes.It will now be apparent that the double cone rocker shoes are capable ofpreventing axial movement of the spindle in either direction bygenerating an hydrostatic pressure which acts perpendicular'to thedouble cone journals, and therefore at opposite acute angles to the axisof the shaft resulting in opposed axial components which prevent axialoscillation of the spindle.

We claim:

1. In precision high speed spindle construction, the combination with aspindle having spaced bearing portions formed thereon, of a supporttherefor having bearing recesses alignable with the bearing portions onthe spindle, a plurality of circumferentially spaced bearing shoescircumscribing the spindle Within each of said recesses, said shoeshaving inner portions corresponding in shape to the bearing portion ofthe spindle engageable thereby and outer faces supportable foroscillation relative to the circumscribing wall of the bearing receivingrecesses, means maintaining said shoes against axial displacement in therecesses, means coupled with said recesses for maintaining the samefilled.l

with lubricant under appreciable hydrostatic pressure whereby uponrotation of the spindle wedge-like oil lms will be produced intermediatethe shoes and bearing portions of the spindle, maintaining the spindlein fixed axial position under varying load conditions, certain of saidshoes -having inner faces reacting in a,l direct radial directionagainst the bearing portions of the spindle for retaining the sameagainst ra dial movement and other of said shoes, each having individualangularly related, portions creating forcecomponents reacting againstthe spindle in opposite balanced angular directions in a radial planewhereby to restrain the spindle against longitudinal movement as well asradial 'displacement of its axis of rotation.

2. In precision high speed spindle construction, @the combination with aspindle adapted to be rotated at high speed, of means for supporting thespindle including a supporting element providing closed bearingreceiving chambers, groups of bearing. elements disposed along thechambers .in circumscribing relation to the spindle, said elements'beingmounted Afor limited oscillatory movement with respect to the spindlewhereby to create wedge-like oil films during rotationof" the spindle,restraining the spindle against radial displacement, certain of saidelements having portions disposed in non-parallel relation with respectto the axis of the spindle, the spindle having corresponding,non-parallel zones ofgeneral frustro-conical type opposing the faces ofsaid bearing members, and means for maintaining the entire series ofbearing elements submerged in lubricating medium under hydrostaticpressure whereby the wedge-like films created on rotation thecombination with a housing member having' spaced bearing receivingrecesses of la spindle extending transversely of the housing and intosaid p an oscillatable non-translatable outer connection with thehousing and having their respective inner faces shaped to conform to theadjacent included bearing portion of the spindle, and means formaintaining the housing and bearing chambers lled with lubricant underappreciable hydrostatic pressure whereby on rotation of the spindleinterposed wedge-like lms will be created between the respective bearingmembers and the spindle, steadying the same at spaced points againstradial displacement of the axis of rotation thereof under varying loadconditions and simultaneously reacting on the tapered zones thereof toprevent longitudinal displacement of the spindle.

4. 'I'he combination with a rotary spindle having opposed tapered zonesproviding frustro-conical bearing portions, of a precision mounttherefor including a support having a recess adapted to circumscribe thezones in spaced relation thereto,`bearing members interposed between thesupport and spindle disposed in a. series circumscribing the bearingportion of the spindle, each of said bearing members having oppositelyinclined tapered segmental recesses formed in the inner faces thereof inconforming relation to the zones on the spindle, means mounting saidmembers for oscillatory, non-translatory movement with respect to thesupport and means for maintaining said bearing portion of the spindleand circumscribing shoes submerged in lubricant under appreciablehydrostatic pressure whereby a continuous cil film of homogeneouscharacter is produced between all of said bearing members and thebearing portions of the spindle restraining the latter against radialand translatory displacement under varying loaded conditions.

5. A bearing structure of the character described for prevention ofradial and longitudinal displacements of a precision spindle undervarying load conditions, including a spindle having opposed spacedfrustro-conical bearing portions, and a plurality of bearing shoesarranged in circumscribing relation with respect to said portion of thespindle, a supporting member providing a chamber circumscribing saidspindle portion and shoes, means mounting said shoes for individualloscliation in 'a plane transversely of the axis of the spindle, each ofsaid shoes having spaced frustro-conical segments on its inner facesubstantially conforming .to the shape of the spindle for interfittingengagement therewith, the spacing of said portions providing anintervening lubricant receiving groove, and means maintaining thebearing receiving chamber completely filled with lubricant underhydrostatic pressure whereby on rotation of the spindle wedge-like.

lms will be produced between the bearing member andspindle reacting onthe spindle in a di-v rection at an angle to the axis thereof wherebyjointly to vrestrain the same against both radial and longitudinaldisplacements under varying loads.

ALBERT H. DALL. FREDERICK S. HAAS.

